As part of the Draconis Combine counterattack, the Fourth Arkab Legion left Trolloc Prime and raided the Lyran worlds of Ganshoren, Auldhouse, and Arcturus. This strike threatened the supply lines for the Commonwealth thrust into the Combine and forced the LCAF to redeploy troops to defend against these deep strikes.[2] After this raid they redeployed to Camlann.[3]

The Legion fought the Ghost Bears' 115th Striker Cluster on Eguilles in 3052. This was a unique combat because the two units both specialized in fast cavalry style tactics.[5] Both sides on this battle took heavy losses, but the Clan took control of the planet. The Fourth Arkab Legion was able to force the 115th back to their landing zone however, and killed Star Colonel Romano Tseng, the 115th's commander.[5]Tai-sa Kosiridam gave up command of the regiment for this failure, demoting himself to the executive officer position.[6]

On February 12, 3071 several asteroids struck Arkab.[10] The 4th Arkab Legion left their duty station and returned to Algedi to assist in humanitarian relief efforts on the Azami worlds.[11] The 4th only took this action after the Arkab leadership wasn't able to get any help from the Draconis Combine leadership. KanreiKiyomori Minamoto sent several demands and threats to the 4th Legion and all Arkab leaders, but the Legions refused to leave their homeworlds.

After the Jihad, the Fourth Legion accepted a post to Shinoha, near the Lyran Commonwealth and The Republic of the Sphere. This posting is close enough to the Azami worlds in the Republic to calm any fears the Azami of Algedi may have. If not for this, the Fourth would request reassignment to their homeworld to continue rebuilding the world.[13]

The Fourth as of 3145 returned to Algedi to replenish their minor losses from new graduates from the Algedi War College. The Fourth has given it's consent to move to the front lines of the invasion of the Federated Suns, however no timetable has been given for this action.[14]

The Fourth has a fair number of heavy 'Mechs on its roster. They use the lighter machines to lure the enemy into a trap, then offer a standing fight with the heavies while the lighter 'Mechs harass their enemies' flank.[6]

The Fourth Arkab Legion consists of three battalions. Unlike most units, only one third of these units are BattleMech forces; the balance of each regiment is composed of fast armor and infantry units.[21] After the events of the Jihad the Fourth is at approximately 80% of its former strength, making it the largest of the Arkab Legions at the time, and half of the Fourth's equipment featured upgraded technology.[12]

Any member of the Fourth Arkab Legion who has a Gunnery Skill Targeting modifier of 3 (or less) can forgo movement and make a weapon attack during the movement phase at a +1 modifier. Damage from this attack applies at the end of the movement phase, so any weapon destroyed in the targeted unit cannot be fired during the Weapon Attack Phase. Note that because this attack occurs before movement, no movement based targeting modifiers apply. The Legion unit cannot move if it makes this attack.[22]